Learning Forum

[nhanani4]

 

Hi,

I do the simulation ansys aqwa and get this error "Hydrodynamic  interacting structure move  too far from analysis position movement".

Can give suggecting how I can solve this error?

I already try decrease / increase but it still give this error.

I do two other simulation likewise change the width and length structure but still get this error. Can I know why ? Maybe ansys version 2023 R2 is not suitable for my simulation?

Can somebody help me..tq in advance.

 

[Shuangxing Du]

Hydrodynamic interactions between different floating structures are sensitive to the relative positions/orietations between the structures in the hydrodynamic interaction group.  

Are there any mechanism, such as fenders/mooring liners/joints between the structures, to avoid them to collide or to move far away from each other in the model you are studying?

[nhanani4]

i have hinged joint and fender ..

the pic old i use caternory mooring.the latest i use tether mooring.

if i  use structure selection in hydrodynamic diffraction as NONE the simulation can run in hydrodynamic time response ..

but if i select ALL structure selection, the simulation cannot run in hydrodynamic time response and get this error.

my simulation is multibody should choose none or all in structure selection ?

hope u can help me .

 

 

 

 

[Shuangxing Du]

For this model, the hydrodynamic interaction is important.  Could you please try

(1) Also define the fenders at the top sides;

(2) Make the surfaces(highlighted parts) between the gaps to be non-diffraction surfaces.

[nhanani4]

 

I try slice the module and do the non- diffraction part still get this error.

It is mistake because the ordering module? i try ordering the module in design modeler is okay in order . but it cannot update ordering module in model hydrodynamic diffration.

 

[Shuangxing Du]

 

The structures’ orders have no effect on this issue if they are in a hydrodynamic interation structure group. From the error message, the simulation stopped as TIME=0.0, I guess that your joint definition may not be correct, which may connect the wrong structures together.

Please use (your Ansys installation folder)\aqwa\bin\winx64\ags.exe to open your Aqwa model (in your project\TimeResponse.res), which may help you to check the connections between the structures. For example, the structure sequence numbers and the articulation sequence numbers can be displayed in Ags as shown below

You can also display the Hydrodynamic Diffraction model (in your project/ANALYSIS.RES) by ags.exe to check if the relative locations of the structures in HD analysis and HR analysis are the same.

[nhanani4]

I already check using ansys aqwa gs. 

I have few question.

I want to put hinge connector at multi floating structure.It is right the point coordinate that I put exactly side of module?

It look okay for me at workbench. but at ansys aqwa gs only see 1 side connector. the connector look inside the module. I want the connector only located  between two module. How to make the hinged connector put between two module? It look no gap connector.

If I put connector, the mooring attract more to right side before simulation run. What is the problem?

 

[Shuangxing Du]

From your model, the hinge local x-axis (along the hinge axis direction), which should be in the global y-axis, is along the global x-axix. Please also define the hinge connection joint points at the middle of the gap.

[nhanani4]

yes the hinge at x-direction. The hinge gap is 3m. How can I do the gap in ansys aqwa?

[Shuangxing Du]

Define the connection points at the middle of the gap.

[nhanani4]

 I already done like u suggest. the connection point at middle.it connection middle gap at one point.

however i cannot run it. I get this error.

i read other comment in forum said to choose run a pythin script but still get this error.How to solve this error.Tq.

[nhanani4]

I want ask another question about fender. Between gap has fender. But fender b is show however fender located at a not show.

I have the data of fender only stiffness fender 1x10^7 N/m. where should I key in @ calculated the data given.The damping coefficient show is not right. Tq.

[Shuangxing Du]

From Aqwa theory manual, the fender's compression force is calculated by

K1 ~ K5 could be input as Coefficient A ~ Coefficient E. As you only have the linear stiffness value, it could be input as Coefficient A.

Please also see the definition of fender's damping force

the unit of the damping coefficient is in second.

Please check the hinge axices in your model, the hinge local x-axis (in red color below) may not be correct.

[nhanani4]

I already done like u suggest. the connection point at middle.it connection middle gap at one point.

however i cannot run it. I get this error.

i read other comment in forum said to choose run a pythin script but still get this error.How to solve this error.Tq.

[Shuangxing Du]

Have you amended the hinge joint's local x direction?  I have mentioned this problem for several times.

 

[nhanani4]

Sorry for my mistake. I see the wrong simulation.

For the linear arrangement module, I get can run the simulation already. Thank u for helping me.

That simulation that I got wrong is the other arrangement module tandem module. The simulation that can not run. I need to change the position hinged at the x-axis but I do not know how.

where i should change the key in data? In a the data only... I should change data in b,c,d?